Dimming apparatus for fluorescent lamps
First Claim
1. A dimming apparatus of a fluorescent lamp, comprising:
- a fluorescent lamp;
a high frequency power supply for supplying high frequency power to said fluorescent lamp;
a control unit for controlling an output frequency of said high frequency power supply in response to an inputted light dimming signal; and
a coil provided between said high frequency power supply and said fluorescent lamp, for limiting a current which flows from said high frequency power supply to said fluorescent lamp;
wherein;
said dimming apparatus is further comprised of a lamp voltage detecting circuit for detecting a discharge voltage of said fluorescent lamp; and
said control unit intermittently controls the output frequency of said high frequency power supply in such a manner that said output frequency becomes higher than a dimming frequency based on said dimming signal so as to periodically change a current supplied to said fluorescent lamp into a low current; and
when the output frequency of said high frequency power supply becomes higher than said dimming frequency, said control unit sets a lower limit dimming set value based upon a detection voltage of said lamp voltage detecting circuit in order that the output frequency of said high frequency power supply is controlled to become lower than, or equal to a upper limit frequency in accordance with said lower limit dimming set value.
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Accused Products
Abstract
The present invention is to provide a fluorescent lamp dimming apparatus capable of continuously dimming the fluorescent lamp, and capable of eliminating a fluctuation of light outputs, and in particular, capable of turning ON the fluorescent lamp in a low temperature. The fluorescent lamp dimming apparatus is comprised of a lamp voltage detecting circuit for detecting a discharge voltage of the fluorescent lamp, and a control unit intermittently controls the output frequency of a high frequency power supply in such a manner that the output frequency becomes higher than a dimming frequency based on the dimming signal so as to periodically change a current supplied to the fluorescent lamp into a low current; and when the output frequency of the high frequency power supply becomes higher than the dimming frequency, the control unit sets a lower limit dimming set value based upon a detection voltage of the lamp voltage detecting circuit in order that the output frequency of the high frequency power supply is controlled to become lower than, or equal to the upper limit frequency in accordance with the lower limit dimming set value.
13 Citations
11 Claims
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1. A dimming apparatus of a fluorescent lamp, comprising:
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a fluorescent lamp; a high frequency power supply for supplying high frequency power to said fluorescent lamp; a control unit for controlling an output frequency of said high frequency power supply in response to an inputted light dimming signal; and a coil provided between said high frequency power supply and said fluorescent lamp, for limiting a current which flows from said high frequency power supply to said fluorescent lamp;
wherein;said dimming apparatus is further comprised of a lamp voltage detecting circuit for detecting a discharge voltage of said fluorescent lamp; and said control unit intermittently controls the output frequency of said high frequency power supply in such a manner that said output frequency becomes higher than a dimming frequency based on said dimming signal so as to periodically change a current supplied to said fluorescent lamp into a low current; and
when the output frequency of said high frequency power supply becomes higher than said dimming frequency, said control unit sets a lower limit dimming set value based upon a detection voltage of said lamp voltage detecting circuit in order that the output frequency of said high frequency power supply is controlled to become lower than, or equal to a upper limit frequency in accordance with said lower limit dimming set value. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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Specification